1. Field of the Invention
This invention relates generally to cathode-ray display panels and more particularly to a display panel which can operate at a low D.C. voltage.
2. Description of the Prior Art
Various types of display panels have been proposed such as the vacuum photocathode-fluorescent screen type, the electroluminescence-photoconductor type (hereinafter referred to as EL-PC system), the liquid crystal-photoconductor type and so on.
However, the vacuum photocathode-fluorescent screen type has the disadvantages that a high voltage of the order of one or more KV is required, resolution is poor and the cost of manufacturing the photocathode is expensive due to the difficulty of obtaining a good quality photocathode, evey though operated with a D.C. voltage. The EL-PC type, has the disadvantages that an A.C. voltage must be applied in order to cause the EL material to luminesce, photoconductive material resistive to high voltage must be used because the applied voltage is relatively high (an order of 100V), the thickness of the photoconductive layer must be 100 .mu.m or more, the structure of the panel is complicated due to the wire grid electrode and the intensity of luminescence is low. The liquid crystal-photoconductor type has the disadvantages that the liquid crystal is damged by X-rays or ultraviolet rays and that the system requires external light, since the liquid crystal itself does not luminesce and thus its use in the dark is not possible.